For regulating lamps and displays depending on the environmental brightness sensors are required that simulate the brightness sensitivity of the human eye.
Moreover, some displays are switched off as soon as an object comes too close to the display, for instance when a mobile phone is attached to the ear or is put into a bag of a user. The display also should be switched off when a user of the device including the display is too far away, for instance, when the user leaves the workplace and the monitor serving as a display is no longer viewed. This proximity function is mostly realized by an infrared LED in combination with a photodiode, wherein the photodiode detects the reflected part of the IR light, thereby allowing tracking whether an object is near the sensor based on the photo current.
Since the human eye is insensitive both for shortwave (smaller than 400 nm of wavelength) and long wave (greater than 780 nm) radiation, whereas an ideal silicon pn junction is sensitive for any wavelengths less than the silicon bandgap (1.2 eV=1100 nm), it has to be guaranteed that the photon or photo-generated electrons of short and long wavelengths are not detected by the sensor.
U.S. Pat. No. 8,274,487 B2 (by Aptina) relates to color light detection, however without filter, which is described as disadvantageous for the sensitivity. U.S. Pat. No. 9,019,251 B2 (by NXP) is concerned with light detection by two different sensors detecting different wavelengths of the environmental light, wherein the two photo currents are combined in a non-linear manner. The non-existing “synchronism” of the sensitivity of a silicon eye and a human eye is referred to, in paragraph [04].